Piezoelectric ultrasonic atomizers have been used in industrial applications to deliver a fine spray or mist for coating surfaces. One such atomizer is shown, for example, in U.S. Pat. No. 4,337,896 to Berger et al. Manufacturers often require such atomizers to be able to coat large surfaces at a time, and to coat the surfaces both completely and uniformly. One attempt to meet these requirements has been to increase the atomizing surface area of the atomizer. The geometric contour of the atomizing surface of an ultrasonic atomizer influences the spray pattern and density of the particles developed by atomization, and by increasing the atomizing surface area, the fluid flow rate can be increased. Thus, the atomizing surface area can be increased, for example, by providing a flanged tip, i.e. a tip of increased cross-sectional area, which includes the atomizing surface, and the spray pattern and density of the atomizer can be further affected by selecting the contour of the tip.
Known atomizers typically utilize a flanged tip which directs the fluid to the surface to be coated in a cylindrical or conical spray pattern. The cylindrical or conical spray patterns, however, invariably create nonuniform concentrations of the atomized fluid on the surface to be coated. Typically, higher concentrations of the atomized fluid are collected on the coated surface in the central area of the conical or cylindrical spray pattern in comparison to the outermost areas, thus forming a nonuniform coating on the surface. These atomizers also typically do not have the ability to apply a substantially uniform stream of atomized fluid to a surface at selected, variable widths.